KRAS and NRAS Mutations in Relation to Microsatellite Status in Colorectal Cancer: A Single-Center Study From Romania

Background/objectives Colorectal cancer is one of the most prevalent malignancies worldwide, ranking third globally and second in Romania. This study aimed to investigate the coexistence of microsatellite instability (MSI) status with KRAS and NRAS mutations in colorectal cancer patients. Methods We analyzed clinicopathological characteristics in 253 patients diagnosed with colorectal cancer between January 1, and June 30, 2024. Polymerase chain reaction (PCR) techniques were used to assess MSI status and detect KRAS and NRAS mutations. Results Among the 253 patients, KRAS mutations were detected in 41.1%, while NRAS mutations were identified in 5.1% of cases. Microsatellite stability (MSS) was observed in the majority of cases (95.7%), with only 4.3% of tumors displaying high microsatellite instability (MSI-H). Of all the analyses undertaken to evaluate associations between clinicopathological characteristics of patients with colorectal cancer and KRAS/NRAS or MSS/MSI-H status, tumor localization demonstrated a statistically significant correlation with microsatellite status (p = 0.032). Conclusions The prevalence of KRAS and NRAS mutations in the studied population was consistent with international estimates, whereas the frequency of MSI-H tumors was lower compared to other European cohorts. A statistically significant association was observed between tumor localization and MSI status (p = 0.032), with MSI-H tumors confined to colonic sites and MSS tumors predominating in the rectum. These data refine the molecular epidemiological landscape of colorectal cancer in an under-studied population and underscore the necessity of larger multicenter investigations to validate and extend these observations.